1. Field of the Invention
The present invention relates to a display apparatus and a projecting apparatus used to display, e.g., a computer image or video image on a large screen.
2. Related Background Art
In recent years, demand has arisen for a projection-type display apparatus with improved brightness. FIG. 15 shows the arrangement of a conventional projection-type display apparatus. Referring to FIG. 15, white light emitted from a light source section 1 passes through fly-eye lenses 3 and 4, PS conversion element 5, and condenser lens 6. A dichroic mirror DM1 transmits a red-band light component and reflects green- and blue-band light components. As the light source, generally, a halogen lamp, metal halide lamp, ultrahigh-pressure mercury-vapor lamp, or the like is used. As a color separation/synthesis optical element, a dichroic mirror, dichroic prism, or the like is used.
The red-band light component transmitted through the dichroic mirror DM1 that exhibits a spectral transmittance shown in FIG. 16A changes its optical path by 90xc2x0 at a total-reflecting mirror M1, strikes a liquid crystal display element 8R through a field lens 7R and a trimming filter TR that exhibits a spectral transmittance shown in FIG. 16C, and is optically modulated here in accordance with the input signal. The optically modulated light component becomes incident on a dichroic prism 9, changes its optical path by 90xc2x0 at the dichroic prism 9, and strikes a projecting lens 10.
On the other band, the green- and blue-band light components reflected by the dichroic mirror DM1 to change the optical paths by 90xc2x0 become incident on a dichroic mirror DM2 that exhibits a spectral transmittance shown in FIG. 16B. As is apparent from FIG. 16B, since the dichroic mirror DM2 has a characteristic for reflecting the green-band light component, the green-band light component is reflected to change its optical path by 90xc2x0, becomes incident on a liquid crystal display element 8G through a field lens 7G and a trimming filter TG that exhibits a spectral transmittance shown in FIG. 16D, and is optically modulated here in accordance with the input signal. The optically modulated green-band light component strikes the dichroic prism 9 and projecting lens 10 in this order.
The blue-band light component transmitted through the dichroic mirror DM2 becomes incident on a liquid crystal display element 8B through a condenser lens 11, relay lens 12, total-reflecting mirrors M2 and M3, and field lens 7B, and is optically modulated here in accordance with the input signal. The optically modulated blue-band light component strikes the dichroic prism 9 to change its optical path by 90xc2x0 at the dichroic prism 9, and then strikes the projecting lens 10.
In the conventional projection-type display apparatus having the above arrangement, polarizing plates necessary before and after the liquid crystal display element 8 are stuck to a transparent glass member such as the protective glass member used for the liquid crystal display element 8, the field lens 7, or the dichroic prism 9.
When the aperture ratio of the liquid crystal display element is low, and the light quantity of the lamp used is small, a transparent glass substrate (thermal conductivity: about 1 W/(mxc2x7K)) suffices, as in the prior art.
The brightness of a screen is recently improved by using a 1.3-type liquid crystal display element having about 770,000 pixels and an aperture ratio of 60% or increasing the power consumption of the lamp. Additionally, liquid crystal display elements are becoming compact.
However, this increases the thermal load on the polarizing plate necessary for the liquid crystal display element, posing another problem of degradation in performance of the polarizing plate.
In addition, when display with priority on the brightness and display with priority on the color reproducibility are realized by a single apparatus, as disclosed in Japanese Patent Application Laid-Open No. 7-72450, the polarizing plate has larger thermal load because display with priority on the brightness uses a wavelength region (about 570 to 600 nm) that is not used for display with priority on the color reproducibility.
To solve the thermal load on the polarizing plate, sapphire (42 W/(mxc2x7K)) having a thermal conductivity about 40 times that of a transparent glass substrate is used as the substrate of the polarizing plate, as disclosed in Japanese Patent Application Laid-Open No. 11-231277. However, if the problem of thermal load is solved simply using sapphire, a 3-CCD projection-type display apparatus as shown in FIG. 15 or a projection-type display apparatus that realizes, by a single apparatus, display with priority on the brightness and display with priority on the color reproducibility, as disclosed in Japanese Patent Application Laid-Open No. 11-231277, requires a total of six sapphire substrates, resulting in large increase in cost.
When the cooling efficiency is increased using a cooling fan, the power consumption of the cooling fan increases. Especially, when display with priority on the brightness and display with priority on the color reproducibility are realized by a single apparatus, as disclosed in Japanese Patent Application Laid-Open No. 7-72450, it is not preferable because cooling must be set in consideration of display with priority on the brightness, where the light quantity increases, while cooling is wasteful for display with priority on the color reproducibility.
The power consumption of the cooling fan may be changed between display with priority on the brightness and display with priority on the color reproducibility. However, a system for switching the power consumption must be incorporated, resulting in an increase in cost or space.
It is therefore an object of the present invention to provide a display apparatus which has a means for changing the color purity of at least one of a plurality of color light components, in changing the color purity of at least one color light component, can reduce the thermal load on the polarizing plate, and can reduce the cost by decreasing the power consumption of a cooling fan.
In one aspect of the invention, a display apparatus for forming a color image by illuminating one or a plurality of display elements with light from a light source and modulating a plurality of color light components having different colors by the display elements, comprises means for changing a color purity of at least one of the plurality of color light components, and a polarizing plate in an optical path of the light component whose color purity is changed by said color purity changing means, wherein said polarizing plate has a transparent substrate including a material having a thermal conductivity higher than 2 W/(mxc2x7K).
In another aspect of the invention, said color purity changing means can adjust whether a light component in a specific wavelength region reaches the display element.
In another aspect of the invention, the light source has a peak at a certain wavelength of the specific wavelength region.
In another aspect of the invention, the certain wavelength is 570 to 600 nm.
In another aspect of the invention, the light source comprises a high-pressure mercury-vapor lamp, and the certain wavelength is about 580 nm.
In another aspect of the invention, said color purity changing means comprises a dichroic mirror.
In another aspect of the invention, the transparent substrate is essentially made of one of sapphire and fluorite.
In another aspect of the invention, the transparent substrate includes a material having a thermal conductivity higher than 5 W/(mxc2x7K).
In another aspect of the invention, the transparent substrate is essentially made of a material having a thermal conductivity higher than 2 W/(mxc2x7K).
In another aspect of the invention, the display apparatus further comprises a plurality of dichroic mirrors for separating white light from the light source into the plurality of color light components having different colors.
In another aspect of the invention, the display apparatus further comprises a plurality of image elements arranged in correspondence with the plurality of color light components having different colors, and a plurality of dichroic mirrors for combining image light components from the plurality of display elements.
In another aspect of the invention, the display apparatus further comprises a plurality of display elements arranged in correspondence with the plurality of color light components having different colors, and a dichroic prism for combining image light components from the plurality of display elements for modulating the plurality of color light components.
In another aspect of the invention, said dichroic prism is formed by bonding four prisms using an adhesive to have wavelength selection/reflection layers substantially perpendicular to each other.
In another aspect of the invention, said color purity changing means inserts/removes an optical element to/from an optical path of at least one of the plurality of color light components or changes a posture of the optical element.
A projecting apparatus according to one aspect of the invention comprises the display apparatus set out in the foregoing, and a projection system for enlarging and projecting an image formed by the display apparatus.
In another aspect of the invention, a display apparatus for forming a color image by illuminating one or a plurality of display elements with light from a light source and modulating a plurality of color light components having different colors by the display elements, comprises means for changing a color purity of at least one of the plurality of color light components, wherein one of the one or plurality of display elements is in an optical path of the light component whose color purity is changed by said color purity changing means, and said one display element has a transparent substrate essentially made of a material having a thermal conductivity higher than 2 W/(mxc2x7K).
In another aspect of the invention, a display apparatus comprises a light source, one or a plurality of display elements illuminated with light from said light source, said display elements forming an image by modulating a plurality of color light components having different colors, and one or a plurality of polarizing plates arranged in an optical path of the light from said light source to equalize polarizing directions of the light components, wherein at least one of said one or the plurality of polarizing plates has a transparent substrate essentially formed from a fluorite.
In another aspect of the invention, the foregoing apparatus further comprises means for changing a color purity of at least one of the plurality of color light components by inserting/removing an optical element to/from an optical path of said at least one color light component or changing a posture of the optical element in the optical path of said at least one color light component.
In another aspect of the invention, said color purity changing means can adjust whether a light component in a specific wavelength region reaches the display element.
In another aspect of the invention, the light source has a peak at a certain wavelength of the specific wavelength region.
In another aspect of the invention, the certain wavelength is 570 to 600 nm.
In another aspect of the invention, the light source comprises a high-pressure mercury-vapor lamp, and the certain wavelength is about 580 nm.
In another aspect of the invention, said color purity changing means comprises a dichroic mirror.
In another aspect of the invention, the transparent substrate includes a material having a thermal conductivity higher than 5 W/(mxc2x7K).
In another aspect of the invention, the transparent substrate is essentially made of a material having a thermal conductivity higher than 2 W/(mxc2x7K).
In another aspect of the invention, the foregoing apparatus further comprises a plurality of dichroic mirrors for separating white light from the light source into the plurality of color light components having different colors.
In another aspect of the invention, the foregoing apparatus further comprises a plurality of image elements arranged in correspondence with the plurality of color light components having different colors, and a plurality of dichroic mirrors for combining image light components from the plurality of display elements.
In another aspect of the invention, the foregoing apparatus further comprises a plurality of display elements arranged in correspondence with the plurality of color light components having different colors, and a dichroic prism for combining image light components from the plurality of display elements for modulating the plurality of color light components.
In another aspect of the invention, said dichroic prism is formed by bonding four prisms using an adhesive to have wavelength selection/reflection layers substantially perpendicular to each other.
In another aspect of the invention, a projecting apparatus comprises the foregoing display apparatus and a projection system for enlarging and projecting an image formed by said display apparatus.
In another aspect of the invention, a display apparatus comprises a light source, one or a plurality of display elements illuminated with light from said light source, said display elements forming an image by modulating a plurality of color light components having different colors, wherein at least one of said one or said plurality of display elements having a transparent substrate is essentially formed from a fluorite.
In another aspect of the invention, the foregoing apparatus further comprises means for changing a color purity of at least one of the plurality of color light components by inserting/removing an optical element to/from an optical path of the at least one color light component or changing a posture of the optical element in the optical path of the at least one color light component.
In another aspect of the invention, said color purity changing means can adjust whether a light component in a specific wavelength region reaches the display element.
In another aspect of the invention, the light source has a peak at a certain wavelength of the specific wavelength region.
In another aspect of the invention, the certain wavelength is 570 to 600 nm.
In another aspect of the invention, the light source comprises a high-pressure mercury-vapor lamp, and the certain wavelength is about 580 nm.
In another aspect of the invention, said color purity changing means comprises a dichroic mirror.
In another aspect of the invention, the transparent substrate includes a material having a thermal conductivity higher than 5 W/(mxc2x7K).
In another aspect of the invention, the transparent substrate is essentially made of a material having a thermal conductivity higher than 2 W/(mxc2x7K).
In another aspect of the invention, the foregoing apparatus further comprises a plurality of dichroic mirrors for separating white light from the light source into the plurality of color light components having different colors.
In another aspect of the invention, the foregoing apparatus further comprises a plurality of image elements arranged in correspondence with the plurality of color light components having different colors, and a plurality of dichroic mirrors for combining image light components from the plurality of display elements.
In another aspect of the invention, the foregoing apparatus further comprises a plurality of display elements arranged in correspondence with the plurality of color light components having different colors, and
a dichroic prism for combining image light components from the plurality of display elements for modulating the plurality of color light components.
In another aspect of the invention, said dichroic prism is formed by bonding four prisms using an adhesive to have wavelength selection/reflection layers substantially perpendicular to each other.
In another aspect of the invention, a projecting apparatus comprises the foregoing display apparatus and a projection system for enlarging and projecting an image formed by said display apparatus.
In another aspect of the invention, a display element comprises a transparent substrate essentially formed from fluorite, and a driving section formed on said substrate.
In another aspect of the invention, a polarizing plate for equalizing polarizing directions of incident light components and outputting the light components, comprises a transparent substrate essentially formed from fluorite and a polarizing film formed on said substrate.